1. Field of the Invention
The present invention relates to a semantic-based search system and a search method thereof and, more particularly, to a semantic-based search system providing an interpretation alternative of a keyword according to a keyword input, and a search method thereof.
2. Related Art
In an existing search method of a Web searching engine, when a user inputs a keyword desired to be searched, a search statement denoting a keyword conforming to a keyword within content of the search statement (or content) or meta-data added to a search sentence is searched. Thus, since a search sentence identical to a keyword is searched according to an input of a keyword, there is no need to interpret a meaning of a search sentence expressed by a relationship between keywords.
However, an existing keyword conformity-based search method has confronted with a limitation according to simple searching, so a semantic-based search scheme has been studied. Here, the semantic-based searching scheme is a searching scheme of interpreting a meaning of a search sentence on the basis of relationships between and among entities denoted by input keywords, and searching data conforming to the interpretation.
Also, terminal devices with which users execute search application extend to terminal devices having restrictions to a sentence input interface, such as a smart phone, a tablet personal computer (PC), a smart TV, and the like, in addition to a PC. In a terminal environment of these terminal devices, a search sentence is input through a Qwerty keyboard, or the like, displayed on a small screen because they do not have a dedicated keyword for inputting a keyword. In case of recent enlarged terminal devices, a keyword is input through a Qwerty keyboard, or the like, displayed on a small screen, only a key word (or a necessary word), while omitting a verb, or the like, rather than inputting a complete natural language sentence, is input in order to minimize the number of times of inputting a keyboard. Thus, input of only a key word according to the input scheme in the limited input environment makes it difficult to interpret a meaning thereof because there is no information regarding a sentence structure.
Meanwhile, Korean Patent Laid Open Publication No. 10-2012-0053253 entitled “Hybrid semantic search system and method” discloses a semantic-based search system using a semantic-based searching scheme.
The related art “Hybrid semantic search system and method” includes determining a type of a query received from a user terminal, performing keyword searching on a query when the query input by a user is a free query; determining whether to perform semantic-based searching on the query on the basis of keyword search results with respect to the query and performing semantic-based searching using ontology on the query, and providing results of the performed semantic-based searching to the user terminal.
However, in the case of the related art “Hybrid semantic search system and method”, the number of keywords input by a user is fixed and a partial graph conforming to a combination of types of knowledge base entities to which each keyword is mapped, e.g., a combination of an instance, properties, and a number of classes, is searched from a knowledge base, having a problem in that interpretation alternatives of a keyword a user wants to substantially search cannot be accurately derived.